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This guide covers the ESSENTIAL issues with KV6 engine in 2.0 150, 2.5 160, 2.5 177 2.5 180 and 2.5 190 outputs as the issues with them are all common regardless of power output or capacity size.

A history of the KV6

First introduced into the Rover 800 series the engine was designed and developed by Rover at Longbridge to replace the Honda 2.7l V6 engine which was about to become non-compliant with tightening emissions legislation.

The original unit was designed for low volume production and hand built but was later significantly redesigned to fit into the smaller Rover 75's bonnet, although performance remained similar and you could almost call them two separate engines.

At introduction, the engine enjoyed considerable technological advancement compared with its competition, most notably being the lightest and shortest v6 in its class. It has fully automatically tensioned timing drive belts and adaptive Siemens EMS2000 engine management. The fuelling and ignition timing are constantly varied to match the load on the engine to improve refinement.

The engine boasts Variable Geometry Induction, whereby air induction pipe lengths vary to optimize engine torque in response to different engine and road speeds (commonly refereed to as the inlet manifold and VIS motors), aiding refinement and efficiency. Although it bears the name of K Series, the engine has almost no components in common with the 4 cylinder version.

The V6 engine is fitted with four overhead camshafts driven by synchronous tooth belts. It has a single, long, serpentine belt at the front driving the inlet cams and also the coolant pump. The exhaust cams are driven by short link belts driven from the ends of the inlet cams at the rear of the engine. The system was a joint development between Dayco (belt supplier) and Rover. The rear link belts do not incorporate any tensioning device. Belt tension is maintained by very careful control of belt length and the pulley pair is pre-tensioned during fitting. The front belt drive is tensioned by a spring loaded tensioner pulley incorporating a hydraulic damping element.

An unusual feature of this system is that it incorporates "floating" inlet cam drive pulleys that are not directly keyed to the shafts. This means that special setting tools are required to establish the cam timing before the pulley fixings are tightened. This requirement is the result of the complexity of the cam drive train.

In addition to the length and thickness tolerance of the belts, the accuracy of the cam timing is also affected by the positional and diameter tolerance of each pulley and the thickness of each major engine casting. The result is that the required degree of timing accuracy could not otherwise be maintained and typically why the cost for the timing belts on the KV6 is so high.

One of the most immediately noticeable features of the KV6 is its distinctive, quietly growling engine note. Infact when MG-Rover when racing with the 2.0 ZS touring car, many commented n the engine having the most fantastic sound in touring cars since the days of the Ford RS500.

The difference in the 2.5 V6 160/180/190 power levels explained

Three "core" versions of the 2.5 quad-cam KV6 engine are offered in the range (the 2.0 24v V6 150 in Rover 75 only). For the ZT only 180 & 190 2.5-litre models, several special features have been engineered to achieve the enhanced power output and drive ability from these engines. The 190 V6 has 190Ps, and increased torque of 245Nm.

Note there are changes between the ZT 180 V6 auto, over the 2.5 V6 180 models used in the Rover 75 and MG ZT 180.

Beginning with the induction system, the ZT 190 air cleaner has an 80mm diameter intake duct in place of a 70mm duct, and a new intake diffuser. This provides a smoother airflow with less than half the usual pressure drop; it has also been tuned for a more sporting induction sound. Internal engine changes include a new inlet cam profile, advancing the inlet valve opening and improved porting.

A further contribution to the performance boost comes from exhaust system on the 190 model, with 60mm diameter pipework in place of 57mm, new low-restriction metal-based starter and main catalysts and a modified rear silencer unit. This silencer has larger-bore internal pipes, twin straight tail pipes and a mechanical valve, which responds to exhaust pressure at around 4500rpm to by-pass the internal baffles.

The ZT 180 & 190 engines have specially designed MG throttle cams and engine ECU software to provide the right sports car feeling of responsiveness to the accelerator pedal, with a deliberate reduction of the normal throttle on/off damping. Also common to both ZT engines is an enhanced cooling system, with 20% greater cooling intake area, improved-flow radiator and top hose configurations and a new plate-type oil/water oil cooler replacing the oil/air heat exchanger.

A note should be made that the MG ZT 2.5 160 V6 is actually a standard Rover 2.5 177 V6 engine but has been deliberately restricted by MG Rover at the time. The difference in restriction is as follows.

1 - Exhaust - The exhaust systems bore diameter from the manifold back has been reduced by several milimeters down to 57mm like the 180 HOWEVER the rear back box on the 160 is much more restricted than the 180 and 190 exhausts.

2 - Induction - The OEM 160 V6 air intake has some "strangling" on the engine. The air intake system has a restricting trumpet in it in the airbox which obviously slows the engine air intake. This can improve the airflow with this simple modfication that I wrote below for removing it.

3 - ECU Engine map - Obviously with the 160, will have a differing remap than the 177 cars. The VIS motors work on ALL V6 models, 2.0 and 2.5. Its the Rover 150/160/177/ & ZT 160/180/190 map that controls their efficiency.

If you can find a willing T4 diagnostic owner whos able to get the car to accept ZCS codes, and get Xpart to recalculate the codes for the car to be a Rover 75 180 (177bhp and it must be a manual otherwise the car will look for the automatic gear box) you can do that however its EXTREMELY TRICKY and most times T4 owners wont cover the work.

Additionally in the future any time the 160 engine is plugged into diagnostics the car will be recognized as a Rover 75 177 V6 if this is done.

Common Problems and Costs

Brace yourself, the KV6 can be a horrifically expensive engine if it goes wrong or has been poorly maintained. Now by horrifically I mean by the price of a second hand car which all our cars are. Few V6 cars will cost more than £6000 now and many are as little as £600 for an early one and below ive listed the reasons why they appear to be such a bargain to the uninformed buyer.

Sticking Throttle in Freezing Weather

A simple fix, but a dangerous one should you find yourself unprepared for it or if your loved one is driving the car. Thanks to a poor design flaw in how air, water and dirt circulates around the engine, you can often find in the colder months your throttle cable will stick when your driving the car due to moisture and dirt freezing.

Now this can be mild and feel like cruise control, or whenever you change gear, cause the car to hit the limiter and rev significantly. I was caught out by this myself on my first ZT and it scared the life out of me at the time as it was snowy weather.

It is actually prevented rather simply. Petroleum Jelly is all you need and some WD40. Open the bonnet and spray the throttle cable, throttle motor mechanism in WD40, let it soak for a bit, and then give the cable and motor a good dollop and smear it around the mechanism and cable etc.

You can actually lift the throttle cable out, as its only held in place with a black square which pops in with little force, which you can use for adjusting the idol of the engine simply by turning it up or down the thread as you need (this is actually handy to make the engine a bit more responsive should you wish to sharpen your throttle response).

Coat the whole area when dry and you will have no problems in the winter months, especially when they where as bad as 2011! Top it up as necessary and job done, and simple and most importantly, safe.

Timing Belts

This is the big one, and often why many KV6 engine cars are scrapped. As mentioned above, the timing system for the engine is very advanced and the servicing of this reflects it.

The belts are ment to be done at 6 years/90000 miles which ever is sooner.

This is a really expensive job sadly, and typically in the region of £500 to £800 depending on what needs replacing including the cost of the kit, which is around £200 to £400 depending on parts and sourcing, and its not something to be taken on light hearted due to the nature of the KV6 engine. However many mechanically competent owners have been giving this a go and advice is in the forum.

A water pump failure for example, means belt replacements and such, so if your getting it done replace everything attached to the belts Ive seen several snapped belts now resulting in engine destruction.

Ive been a victim of the pretensioner failing on my first ZT V6, despite the fact the belts where done prior to my purchase, however they hadn't replaced the pretensioner which damaged my big end but the engine was drivable but the engine was essentially scrap.

A Rover 75 / MG ZT with a KV6 without this work done will sell for various prices, but even with the work done, it doe not often add significant value to the car, so consider this before you complete the work if you plan to sell in the future.

Thermostat

An issue that started to rear its head in the last few years has been the Thermostat housing failing, or the Thermostat failing outright on the KV6 engines.

Sometimes it cracks, or splits or the pipes around it can leak, but the easist way to check is to remove the engine cover using a long socket and look between the "V" of the engine to the left side, there is your thermostat, if that starts to leak it can be a heart ache and left unsorted it will do severe damage to the engine.

Using this image below, you can look under the pipe labeled "3" and you will find the thermostat.

It should be noted that pipe "3" often breaks at the T junction and should be replaced completely, or if your cheap like me, scrape out the inside of the plastic from the three pipes and use a copper T piece from your local B and Q. 22,000 miles later and mines still fine.

Be careful when sourcing a replacement as people mis-sell the KV6 housing as suitable for both Freelander KV6 and 75/ZT KV6 which infact they are not, as the picture below shows. Note the CORRECT housing for our cars will be stamped with "PEM101050" as the part number and cost you around £30 new, or £60 for the complete kit with pipes which are worth doing also.

A job that you can do yourself, there are guides in the forum and HOW TO section, and should you not wish to, a mechanic would change no more than £100 to complete the job unless Thermostat has done damage, then the headgaskets would be replaced to be on the safe side.

Note this is not the common headgasket failure as like the 1.8 engines, but rather will occur when the thermostat has boiled the engines insides significantly.

When toping up the coolant system, you should use O.A.T coolant, which is pink. The silicate free, organic acid technology (OAT) provides superior engine protection and is compatible with all vehicle manufacturers' colours of OAT coolants.

This was the specification given by Rover and MG-Rover, and Halfords and such sell it. However your Vauxhaul dealership will also sell it 100% pure (to dilute 50:50 yourself) at a much cheaper price.

Inlet Manifold / VIS Motors

The final major issue with the KV6 engine after timing belts and thermostat is "The rattle of death" as some describe it, the rest of us describe it as a failed inlet manifold. The Inlet manifold controls the amount of air being let into the engine to vary to optimize engine torque, without it worknig correctly, the engine will feel very sluggish at all speeds.

This is the section at the top of your KV6 engine and removed looks like this.

Listen for a tappety noise from inlet manifold (black plastic bit at top of engine at rear) which will tell you if you entire manifold need replacing. You may here a small rattle on start up for maybe 15/20 seconds even if engine is cold or warm, that is perfectly normal and should be ignored, however when it continues and sounds like a bag of nails in a washer machine it will be obvious.

These inlet manifolds can not be repaired and much be replaced, it will sound like this if it has failed, sometimes it can sound like the entire engine is dying, but its a simple replacement job that would take a mechanic a few hours.

Replacement can range between £100 from a scrappy to £300-500 new depending where you source it and it is essential that the inlet manifold gasket is replaced and correct sealant else you will hear a slight hissing when the engine is idling after you reassemble.

With regards the VIS motors these can fail due to oil in the actuators of the motors, built up from the engine itself, a bad design flaw sadly. At 3500 rpm there should be a distinct surge in power, notable in 2nd/3rd gear especially, if theres not your VIS motors will need replacing most likely.

Second hand ones are around £30 and are a very easy fix for anyone, a few screws and your flying, literally. The difference to a car without operating VIS motors is significant.

General servicing costs and maintance

So if all of that hasnt scared you off then heres the good news now, assuming you have covered all the regular issues listed then actual maintenance of the KV6 engine is actually quite inexpensive providing you service it when you should.

Depending on usage, a 12,000 mile service is perfectly acceptable, some do around 6000 miles if the car is used less frequently, I myself do my own KV6 every 6 months regardless of millage.

The basic oil filters, engine filters and such are quite cheap and the dearest thing is actually the spark plugs. You must make sure you use IRIDIUM tipped spark plugs, a set of six will cost you around £40 but are good for around 60,000 miles minimum. Access to the rear bank of spark plugs is slightly awkward but not impossible and doesnt require the removal of the inlet manifold.

As mentioned in the Thermostat section, use of the correct coolant is recommended so use O.A.T coolant, which is pink in colour. Save yourself over Halfords prices and buy none-diluted from your local Vauxhaul dealership. 5 litres will cost you about £22 maximum and when you mix it 50:50 gives you 10 litres of coolant.

Various oil grades are required for different power outputs of the KV6, I have listed them with each engine in the specifics below to ensure no confusion arises.

General Engine information

The various technical specifics of each engine is listed below, please use it as a guide, note check the "8th" digit of your cars vin number to confirm your engine size and power output as there are few obvious signs as to which KV6 is fitted.

FIRSTLY, IT SHOULD BE STATED THAT THIS CAR WAS NEVER SOLD IN THE UNITED KINGDOM OR IRELAND. And with good reason but we will get to that....

A $10,000 extra in July 2004, well Australian Dollar, which was about the same as about £6400 roughly in 2004 exchange rate. Based on the 180ps/177bhp engine (not the 190 strangely enough), the high efficiency, low-boost twin-screw type supercharger had been developed locally through Sprintex Superchargers based in Perth, Western Australia.

This conversion involves the replacement and inclusion of a number of components, including a a fabricated inlet manifold to replace the original unit, control ECU, boost bypass value, a secondary fuel injector, mounting brackets and of course the twin screw supercharger.

The low boost will help prolong the life of the engine.......... or so they said. Multiple failures and recalls due to lack of fueling, not enough oil flowing correctly in the engine, additional oil sumps for the charger the list kept going on and on.

Basically MG-Rover never signed off on the engine in the UK but that doesnt mean there are not examples of it in ZS and ZT cars, but they are very rare and the cost is simply staggering compared to buying a V8 ZT for example.

This guide covers the ESSENTIAL issues with M47R diesel engine in 2.0 115 and 131 outputs as the issues with them are all common regardless of power output.

A history of the M47R

You will always hear people saying that the Rover 75 /MG ZT has a BMW engine, well thats only true if it has a diesel engine in the car. The 2.0 litre diesel unit was BMW's common rail motor, designated M47R.

M47R used in the 75/ZT was was based on the early 1998 - 2001 BMW "M47D20" diesel engine except mildly de-tuned compared to the power outputs that BMW had.

Whilst it had the same core engine block it had many parts redesigned for the front wheel drive gearbox and transverse fitting into the engine bay.

For example, in the BMW 320d's of the time, the engine was notoriously unreliable, yet the diesel 75/ZT version suffered none of the common problems. Chief among the BMW 320d cars problems was a 'swirl flap' mechanism employed within the inlet manifold. These consist of a number of butterfly valves within each individual inlet tract. Unfortunately these flaps are secured to an actuating rod via 2 small screws.

When this happens they can end up being drawn into the respective cylinder causing significant damage to both piston, cylinder head and valves. If unlucky further damage can be caused to the turbo if the screw then makes it's way through the exhaust valve into the manifold and subsequently into the turbo.

So much for the "ultimate driving machine" and yet another example of peoples foolishness that assuming certain brands are better cars by the badge.

Back to the M47R fitted to the 75/ZT, the engine was available in two power outputs (115 bhp and 131bhp details covered below) and does not suffer the kind of service and maintenance bills that the KV6 has, however there are common faults to watch out for and they have been listed below.

M.P.G

Arguably the main reason for purchasing a diesel 75/ZT would be the fuel economy that the car can produce. Listed at the bottom of this is all the "official" MPG figures and stats for all the engines, in various powers with the various gearbox types.

It is safe to say that you will comfortably get a minimum of 40 MPG out of your diesel engined car. Now do not panic, I said a minimum. More realistic for everyday driving is a solid 50mpg with the automatic gearbox and a 55ish MPG for the manual gearbox.

Again driving style s the biggest factor but engine condition is essential on the engines for keeping the MPG up, and the common faults (listed below the Power Output section) will help explain what is wrong if your MPG figures are perhaps not so good as you hoped.

Power Outputs 115/131bhp

As both the 115 and 131 engines are totally identical bar the electronic control mapping (the ECU), they will be treated as a single engine in this section specific to them and specific faults to watch for.

Cars are badged as CDT and CDTI but that does not mean a CDT is 115 or a CDTI is a 131bhp engine. The 8th Chassis number should be "H" but that doesnt change for either power output.

Any X-part dealership with a T4 Rover Diagnostics machine can change the ECU map for you. If you have the remap it should have a sticker on the B pillar on the drivers side of the car about a third of the way up.

This is not always guaranteed however, so check the logbook as it will state 115 or 131. If you wish to upgrade your 115 to a 131 (which is highly recemmended by all owners), it will cost you £199 plus an hours labour at around £35.

This remap is sometimes referred to as ''the X power remap'' and was a Rover / MG optional extra and should not cause you any problems with your insurance once declared as they simply see you car as being a 131 model instead of the 115 model.

More power is available from tuning the diesel engines, up to 170ish bhp with various modifications and searching the forum will help you find guides on parts and fitting and costs.

Common faults of the Diesel M47R engines

Oil leak at radiator

A annoyance but a common fault as it will happen to every car at some stage, when the intercooler "o" rings fail and they do all too often then there is always an oily mess at the front passenger side under the bonnet. It is hours work maximum job to replace them and fortunately there are upgraded "viton o rings" that can be purchased. For maybe 100 users that comment on this leak, only 1 would need an inter cooler to be replaced and thats usually when they have neglected it for a very long time!

The diesel engine uses a cam chain, rather than a timing belt mechanism. Cam chains usually do not require replacement unless they become loose and noisy.

If there a rattle noise (like nails in a washer machine) when the engine is ticking down in the driver’s side of the engine bay then more than likely this is the issue and then it is likely the cam chain has stretched.

The cam chain is inside the engine and replacement is very labour intensive as the chain was designed to last the life of the engine. This is not a "common fault" as such, but it is perhaps the first most easiest fault to diagnose when you first examine the car.

Sluggish at low revs

People used to say diesels where slow, this is very untrue of a healthy 75/ZT diesel engine. Providing quick and brisk acceleration that would embarrass most boy racers!

Typically you wil find that if the engine is sluggish from lows revs around 1250RPM in all gears then it is likely a simple cause. The MAF (mass air flow sensor) is past its sell by date and will need replacing, this can be expensive depending where you purchase a replacement.

The best way to test this is to disconnect the MAF and then start to drive the car, you will find the power increases immediately and that will be your solution. You should not however drive the ca like this for any distance as it may cause serious engine damage if left disconnected continuously.

Prices of £130 wouldnt be unheard of, which is shocking when you can buy similar ones from ebay much cheaper. A lot of people simply remove it, and clean is, and refit it!

The alternative is a MAF from another car with a MAFAM compensator. This forum is filled with discussion about the matter and anyone who does it will recommend it.

Excessive Black Smoke / Poor MPG

Again, as the cars warm and when you accelerate, you might notice a small whisp of black smoke. This is normal, however you may notice a trail of smoke under heavy acceleration and this is usually a warning sign that either the MAF has failed (as above), or is over fueling the engine (again, clean or replace).

Also, the Exhaust Gas Recycling valve (EGR valve) after a few years of driving is likely to be restricted due to being blocked by sooty and oil vapour and deposits blocking the airflow. The EGR needs cleaning or replacing or bypassing.

The benefits of bypassing vary, as it means its zero maintenance in the future, and some owners report the cars idol gentler. Again, ask opinions on the forums and where to purchase the by pass.

Dip Stick test

A simple test that can show a engine on its way out. When the engine is running, does oil spit out of the top of the dipstick pipe when the dipstick is removed?

If yes, you have a problem that could be serious. The PCV (positive crank case ventilation valve aka oil filter) hasnt been changed in time with the last service, or with recent services and needs sorting asap.

Do not attempt to clean the filter, it must be replaced and everytime an oil change is done after that.

If this is left unattended for long periods serious engine damage can occur. A blocked PCV valve will cause the oil to be expelled out of the dipstick tube when the engine is running and this can cause serious engine damage.

Fuel pumps

There are two fuel pumps on the diesel cars, the inner one (which is below the passenger rear seat, you hear it buzz when you put the key into the ignition to start the car), and the under bonnet pump, under the car bonnet obviously.

These seem to just wear out over time, millage reports are inconsistent but costs of replacing them are not sadly.

If the in tank pump can’t be heard to have a quiet buzz above the rear seat it is likely the in tank pump has failed, this causes the under bonnet pump to fail as it has to do all the work to pump the fuel. The under bonnet pump will make a large amount of buzzing ad noise hen it is doing the work of both pumps and thats the sign its also on its way out.

You can simply check both the pumps using this method given by Jules our resident expert on everything!

There's no need to lift the rear seat to hear the intank pump as most people think.
Disconnect the under bonnet pump (if one fitted) by pressing tab on the 2 wire plug which just pulls away then.
This isolates the front pump so there is no confusion between which pump you are listening to.
Providing the surrounding noise level isn't too great, open the fuel flap and stick your ear around the filler neck.
The Intank pump can be heard quite clearly for 50 seconds then switches off (Ignition ON engine not running)

Same 50 seconds test applies to underbonnet pump also after it had been re-connected

Diesel Thermostat

Simply the diesel engine runs best when up at full temperature (eg on a long motorway drive, or puling a caravan), and short driving/inner city driving wont allow the engine to get up to correct temperature to get your MPG to the best. Many report between 6 to 8 miles before the engine is up to full working temps.

Without boring you with science, it is simpler to explain that the diesel engine is very efficient at keeping cool. Too efficient unfortunately, this has lead to many diesel cars suffering a thermostat failure (it getting stuck open or stuck closed).

If the thermostat is closed, then there is no water going to the radiator, and it doesen't matter how good or bad the radiator is. The only cooling you will have comes from the heater matrix, if it is open, and from cooling around the engine as well as from heat lost in the exhaust.

Obviously, a stuck thermostat in an open position will make matters worse. As you then have an amount of water being cooled because of the radiator.

One simple solution to this is actually the OEM full burning heater, (which can be remote controlled) which will preheat a diesel engine for you for a few minutes before you begin your journey. This is especially useful in the winter as not only is your car defrosted from the heater being active, but the car is nice and warm on the inside.

The downside of this, is a hit on your MPG but only as much as you use it.

A false LOW reading seems to be obtained whenever the dipstick is left in place after running the car and returning home. Even reading the dipstick the morning after with the engine now completely cold, the first time the stick is extracted will give a false LOW.

On wiping and re-inserting immediately afterwards , a correct FULL reading will be obtained. Also, If the dipstick is taken out and left on top of the engine whilst in the garage, then on reinserting a correct FULL reading will be obtained. Similarly ANY reading taken after first removing the dipstick and re-wiping will be CORRECT.

General servicing costs and maintenance

So if all of that hasnt scared you off then heres the good news now, assuming you have covered all the regular issues listed then actual maintenance of the diesel engine is actually quite inexpensive providing you service it when you should.

Depending on usage, a 12,000 mile service is perfectly acceptable, some do around 6000 miles if the car is used less frequently, but its up to yourself.

The basic oil filters, engine filters and such are quite cheap, changing everything will cost you no more than £50 and the dearest thing is actually the glow plugs which are £20 ish for all four.

Use of the correct coolant is recommended so use O.A.T coolant, which is pink in colour. Save yourself over Halfords prices and buy none-diluted from your local Vauxhaul dealership. 5 litres will cost you about £22 maximum and when you mix it 50:50 gives you 10 litres of coolant.

Use a 10W/40 or 15W/40 oil meeting both ACEA A3 and ACEA B3:96 specifications, and having a viscosity band recommended for the temperature range of your locality.

Additionally, many owners have reports that especially when they top up their diesel engine with some 2 stroke oil into the FUEL TANK with your diesel (roughly 1ml for every litre, or 50ml per tank full roughly) the car behaves and starts much easier. Perhaps a refection of the high sulfur levels in modern diesel for sale on the forecourt.